Some Forum permissions aren't saved when editing and saving

1. Go to a site with at least two sections 2. Go to forums tool 3. Click New Forum 4. Fill Forum Title 5. Don't change permissions 6. Click Save 7. Click "Create a topic?" in the new forum 8. Fill Topic Title 9. Click Save 10. Enter as student of one section (ex: Discussion 1 SMPL101) 11. Enter as student of other section (ex: Discussion 2 SMPL101) 12. Both student can see the forum Right — 1. Click New Forum 2. Fill Forum Title 3. Change permissions: Student -> None one Section (Ex: Discussion 1 SMPL101) -> Contributor 4. Click Save 5. Click "Create a topic?" in the new forum 6. Fill Topic Title 7. Click Save 8. Enter as student of one section (ex: Discussion 1 SMPL101) 9. Enter as student of other section (ex: Discussion 2 SMPL101) 10. Only student of the section one Section (Ex: Discussion 1 SMPL101) can see the forum Right — 1. Go to Forums 2. Click "Forum Settings" in the first forum that we created 3. Change permissions: Student -> None one Section (Ex: Discussion 1 SMPL101) -> Contributor (same permissions second forum) 4. Click Save 5. Enter as student of one section (ex: Discussion 1 SMPL101) 6. Enter as student of other section (ex: Discussion 2 SMPL101) 7. Only student of the section one Section (Ex: Discussion 1 SMPL101) would see both forum 8. Student of the other section wouldn't see any forum. Wrong: Student of the other section can see the forum